Locking pliers are well known in the art. One such conventional device is known as a Vise Grip pliers. These devices have two jaws that may be locked on an object. The over-center locking mechanism is achieved through a fixed jaw attached to a body, a movable jaw pivoted to the body, a handle pivoted to the movable jaw, and a pivoting over-center link between the body and movable jaw that together cooperate to lock the jaws on a work piece when the handle is forced toward the body. The over-center mechanism includes a fine adjustment screw that controls the opening of the jaws over a limited range to accommodate articles of different sizes within the range and permits the over-center mechanism to lock.
Another common variation is known as adjustable and water pump pliers. These allow for a movable pivot location to adjust the jaw size range for a given handle position. Further locking pliers have been combined with an adjusting mechanism to provide an adjustable locking pliers. In this manner a locking pliers can maintain a relatively parallel jaw and fit a wider size range of objects to be gripped. Some designs, for example “auto adjusting” types require careful and unintuitive manipulation of handles of the pliers to adjust or maintain a jaw size.
However the prior attempts to combine locking and size range adjusting features have a required a bulky, inconvenient, or inefficient mechanism. One example is a pliers according to U.S. Pat. No. 3,981,209; a corresponding product is sold by Facom of France as model #509. Another related Facom product is model #500 which includes features of the '209 patent along with features from French patent 1,100,105. These models are not easily adjusted and have a limp handle wherein there is no opening bias upon the lower jaw or the handle to stabilize the tool in a hand. Further without an opening bias there is no feedback for the position of the handle. All of the prior such designs have been awkward in appearance or use. According to the present invention a locking adjustable pliers includes a familiar appearance in a simple and compact design.